This project deals with factors possibly affecting the long-term benefits of the aortocoronary bypass surgery. A comparison of 38 patients who required a second revascularization procedure with over 1000 patients who had satisfactory post-surgery course has revealed, that the former group continued to have high blood lipid levels, higher diastolic blood pressure flowing the first operation and the patients received fewer grafts than the latter group. Histological examination of blocked vein grafts removed during the second surgery has shown development of atherosclerosis in about 50% of the samples. More detailed examination of the pathological changes in the grafts is underway.